"They didn't do it out of religious conviction," assistant US attorney Joseph Gribko told a judge in a federal court hearing. "They did it for money."

Marc Agnifilo, a lawyer for Wolmark, said it is possibly a case where religious law collides with federal statutes, where the crimes they are accused of can be punished by life in prison.

"It's a very complex case. The government says it's all about money, but I don't think that's quite right," Mr Agnifilo said after the hearing, calling coercion and even violence to get husbands to grant religious divorces "an old tradition".

The rabbis and eight other men were arrested after an undercover operation that began in August when two FBI agents, one posing as a woman trying to get a divorce, contacted the rabbis. According to an FBI complaint, Epstein spoke about forcing compliance through "tough guys" who use electric cattle prods and even place plastic bags over the heads of husbands.

The FBI said the price was more than 50,000 dollars (£31,000) and a prosecutor said the organisation involved in the alleged plot had been involved in up to 20 kidnappings over the years.

No pleas were entered and lawyers for some of the defendants sought to minimise their clients' roles in an effort to get them freed on bail or put on home confinement.

Magistrate Douglas Arpert ordered all 10 held in federal custody at least until hearings next week.

The investigation took place in Ocean and Middlesex counties in New Jersey and Rockland County in New York state.

Four of the rabbis' associates were described as enforcers, or "tough guys", as Epstein called the men who helped coerce reluctant husbands.

The undercover agents, including a man posing as the woman's brother, met Epstein at his Ocean County home in August, during which the rabbi spoke about "kidnapping, beating and torturing husbands in order to force a divorce", the complaint said.

"Basically what we are going to be doing is kidnapping a guy for a couple of hours and beating him up and torturing him and then getting him to give the get," Epstein is quoted as saying during the conversation, which was videotaped.

Epstein is also quoted saying he wanted to use a cattle prod to torture the reluctant husband.

"If it can get a bull that weighs 5 tons to move ... you put it in certain parts of his body and in one minute, the guy will know," he said, according to the complaint.

Under Jewish law, if a husband refuses to grant his wife a get, she has the right to sue in rabbinical court. The complaint said that a rabbinical court was held in Rockland County on October 2 as part of the sting, during which the use of violence was authorised.